One study of 48 overweight women on a very-low-calorie diet found that those who followed a weight lifting program maintained their muscle mass, metabolic rate and strength, even though they lost weight (28).

Women who didn't lift weights lost weight too, but they also lost more muscle mass and experienced a drop in metabolism (28).

Because of this, doing some form of resistance training is really a crucial addition to an effective long-term weight loss plan. It makes it easier to keep the weight off, which is actually much harder than losing it in the first place.

Bottom Line: Lifting weights helps maintain and build muscle, and it helps prevent your metabolism from slowing down when you lose fat.

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6

People Who Exercise Sometimes Eat More

One of the main problems with exercise and weight loss is that exercise doesn't just affect the "calories out" side of the energy balance equation.

Exercise May Increase Hunger Levels

One of the main complaints about exercise is that it can make you hungry and cause you to eat more.

It's also been suggested that exercise may make you overestimate the number of calories you've burned and "reward" yourself with food. This can prevent weight loss and even lead to weight gain (29, 30).

Although it doesn't apply to everyone, studies show that some people do eat more after working out, which can prevent them from losing weight (31, 32, 33).

Exercise May Affect Appetite-Regulating Hormones

Physical activity may influence
the hormone ghrelin. Ghrelin is also known as "the hunger hormone" because of the way it drives your appetite.

Interestingly, studies show that appetite is suppressed after intense exercise. This is known as "exercise anorexia" and seems tied to a decrease in ghrelin.

However, ghrelin levels go back to normal after around half an hour.

So although there is a link between appetite and ghrelin, it doesn't seem to influence how much you actually eat (34).

Effects on Appetite May Vary By Individual

Studies on calorie intake after exercise are mixed. It's now recognized that both appetite and food intake after exercise can vary between people (
30,
35,
36,
37,
38).

For example, women have been shown to be hungrier after working out than men, and leaner people may become less hungry than obese people (31, 39, 40, 41, 42).

Bottom Line: How exercise affects appetite and food intake varies between individuals. Some people may become more hungry and eat more, which can prevent weight loss.

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7

Does Exercise Help You Lose Weight?

The effects of exercise on weight loss or gain varies from person to person (43). Although most people who exercise will lose weight over the long term, some people find that their weight remains stable and a few people will even gain weight (44).

However, some of those who gain weight are actually gaining muscle, not fat.

All that being said, when comparing diet and exercise, changing your diet tends to be more effective for weight loss than exercise (45, 46).

However, the most effective strategy involves both diet and exercise (47).

Bottom Line: The body's response to exercise varies between individuals. Some people lose weight, others maintain their weight and a few people may even gain weight.

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8

People Who Lose Weight and Keep it Off Tend to Exercise a Lot

Keeping weight off once you have lost it is hard. In fact, some studies show that 85% of people who go on a weight loss diet are unable to keep the weight off (48). Interestingly, studies have been done on people who have lost a lot of weight and kept it off for years. These people tend to exercise a lot, up to an hour per day (49).

It's best to find a type of physical activity you enjoy and that fits easily into your lifestyle. This way, you have a better chance of keeping it up.

Bottom Line: People who have successfully lost weight and kept it off tend to exercise a lot, up to an hour per day.

9

A Healthy Diet is Also Important

Exercise can improve your health and help you lose weight, but eating a healthy diet is absolutely crucial as well.